In the normal procedure of preparing whole blood samples for typing and other tests, the samples are first centrifuged to separate the blood into its serum and cell components. The serum and cell components are then manually subdivided into smaller portions and placed in a number of test containers, using an eyedropper for distributing the serum and cells into the test containers. Reagents are then added to each container, and time is allowed for reactions to occur.
The reagents are either 1) serum containing antibodies of known type, or 2) cells of known blood types. The reaction looked for is the agglutination or clumping together of single cells into clumps of cells, where the cells can be either those in the reagent or those in the blood sample.